1. Field of the Invention
The present invention relates to agricultural planters, and, more particularly, to agricultural planter row units.
2. Description of the Related Art
Agricultural planters are commonly used implements to plant seeds in soil. An agricultural planter can include a chassis that carries one or more storage tanks carrying seed, and chemical applications that are to be applied to the field during the planting operation, a hitch mechanism that attaches to a tractor or other implement pulled by a tractor, and a tool bar that row units can be connected to so they are carried by the chassis. The planter can also include a pneumatic system carried by the chassis that supplies pressurized air to transport the seeds or other particulate from the storage tanks to the row units.
Each row unit of the agricultural planter places seeds in the field. Typically, the row units are laterally arranged along a length of the tool bar so that as the planter is pulled across the field, each row unit plants seeds at predefined intervals along the path it is pulled across. To plant seeds, the row units perform three main operations as they are pulled: opening a trench in the soil; placing a seed into the formed trench at appropriate intervals; and closing the formed trench to put soil on top of the placed seed. To open a trench in the soil, a furrowing disc system, which may include an opening disc, cuts into the soil and rotates, dislocating soil as it rotates to form the trench. Once the trench is open, a seed is placed in the trench by a metering device which receives seeds from the main storage tank(s) or a row unit storage tank and typically utilizes a combination of differential air pressure, to select the seed, and gravity to place the seed in the trench at predefined intervals along the pulled path so that adjacent seeds in the row are not too close to one another. Pinch wheels carried behind the furrowing disc are pressed into the soil and also rotate as the planter is pulled to replace soil dislocated by the furrowing disc in the trench or dislocate adjacent soil into the trench to cover the seed placed in the trench with soil, as well as pack the soil onto the seed to provide good soil contact. By having multiple row units working in unison as the planter is pulled across a field, many seeds can be effectively planted in an efficient manner.
As the row unit is pulled across the field, a down force is typically applied to the pinch wheels to force the pinch wheels into the soil so that the pinch wheels maintain constant soil contact. The down force can be provided by, for example, a pneumatic cylinder or various types of springs. As farmers try to plant at different times in the season, conditions for closing the formed trench can change. When planting early in the season, for example, difficult soil conditions can require additional down force be applied to the pinch wheel(s) compared to conditions later in the season. A pneumatic cylinder allows the farmer to apply the required down force for early planting, but is typically more expensive and complicated compared to other elements that can provide down force to the pinch wheel(s), such as an extension or compression spring. Further, pneumatic cylinders require more components than springs, such as relatively heavy air compressors, which can add to the weight of the row unit and provide more possible failure points.
What is needed in the art is a way to apply downforce to the pinch wheels while overcoming some of the aforementioned disadvantages.